NPE and CommandExecutionException when creating directory over SSH

When deploying site with mvn site:deploy on multi module project, I get really often (about 90%) the following error :
[INFO] ------------------------------------------------------------------------
[INFO] Building BANACO - Projet principal (POM)
[INFO] task-segment: [site:deploy]
[INFO] ------------------------------------------------------------------------
[INFO] [site:deploy

]
scp://cdxlan025.douane:22/var/jboss/server/archiva/deploy/CID-PORTAIL-DEV.war/site/banaco/1.2.1-SNAPSHOT/ - Session: Opened
Executing command: mkdir -p /var/jboss/server/archiva/deploy/CID-PORTAIL-DEV.war/site/banaco/1.2.1-SNAPSHOT/.
scp://cdxlan025.douane:22/var/jboss/server/archiva/deploy/CID-PORTAIL-DEV.war/site/banaco/1.2.1-SNAPSHOT/ - Session: Disconnecting
scp://cdxlan025.douane:22/var/jboss/server/archiva/deploy/CID-PORTAIL-DEV.war/site/banaco/1.2.1-SNAPSHOT/ - Session: Disconnected
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error uploading site

Embedded error: Error performing commands for file transfer
java.lang.NullPointerException
[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Error uploading site
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:719)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoExecutionException: Error uploading site
at org.apache.maven.plugins.site.SiteDeployMojo.execute(SiteDeployMojo.java:229)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
... 17 more
Caused by: org.apache.maven.wagon.TransferFailedException: Error performing commands for file transfer
at org.apache.maven.wagon.providers.ssh.ScpHelper.putDirectory(ScpHelper.java:232)
at org.apache.maven.wagon.providers.ssh.jsch.AbstractJschWagon.putDirectory(AbstractJschWagon.java:360)
at org.apache.maven.plugins.site.SiteDeployMojo.execute(SiteDeployMojo.java:215)
... 19 more
Caused by: org.apache.maven.wagon.CommandExecutionException: Cannot execute remote command: mkdir -p /var/jboss/server/archiva/deploy/CID-PORTAIL-DEV.war/site/banaco/1.2.1-SNAPSHOT/.
at org.apache.maven.wagon.providers.ssh.jsch.AbstractJschWagon.executeCommand(AbstractJschWagon.java:326)
at org.apache.maven.wagon.providers.ssh.jsch.AbstractJschWagon.executeCommand(AbstractJschWagon.java:379)
at org.apache.maven.wagon.providers.ssh.ScpHelper.putDirectory(ScpHelper.java:228)
... 21 more
Caused by: com.jcraft.jsch.JSchException: java.lang.NullPointerException
at com.jcraft.jsch.Channel.connect(Channel.java:205)
at com.jcraft.jsch.Channel.connect(Channel.java:144)
at org.apache.maven.wagon.providers.ssh.jsch.AbstractJschWagon.executeCommand(AbstractJschWagon.java:305)
... 23 more

It can happen on the main module (pom) or on other module (jar, war, ...).

So automatic SNAPSHOT publishing with Hudson can not work as I would like...

Thanks for any help.